Fertilization and nutrient management trials in peanut

Ongoing studies evaluate the response of peanut to boron {B) and calcium {Ca) fertilization. Products used in the boron study included Borosol-10 (boric acid), Solubor (sodium borate), and Boron Xtra {Custom Ag Formulations, Fresno, CA). Treatments included single applications of Borosol-10 at rates of 0.25, 0.50, and 1.00 lb B acre·1 (0.28, 0.56, and 1.12 kg B ha·1); Borosol-10 split applied at overall rates of 0.50 and 1.00 lb B acre·1 (0.56 and 1.12 kg B ha·1); Solubor applied at 1.00 and 2.00 lb B acre·1 {1.12 and 2.24 kg B ha-1); Boron Xtra applied at 0.02 lb B acre·1 (0.02 kg B ha·1); and an untreated control. Various sources of calcium were evaluated alone or as supplemental treatments. Calcium studies included an untreated control, gypsum {1000 lb acre·1 and 500 lb acre-1), lime {1000 lb acre·1), Black Gypsum {1000 lb acre·1; The Andersons, Inc., Maumee, OH), AgriMend gypsum {1000 lb acre-1; AgriFarm Group, Colorado Springs, CO), and Full Measure Cal {3 gal acre·1; Full Measure LLC, Bristol, RI). Yield and grade responses to treatment were not observed, and minor incidence of B-deficient seed was observed only in one year of the study. While applied B did not affect seed B, applied B described 83% of leaf B variability. Solubor applied at 2.24 kg B ha-1 was the most effective treatment for increasing leaf tissue B, and this high rate did not result in B toxicity. Yield and grade were not increased by Ca treatments, which is likely due to adequate initial soil test Ca levels {>150 mg kg-1). Seed Ca was increased by Ca additions in 2016 and 2017 with 57 and 36% of the variability in seed Ca explained by applied Ca rate in each year, respectively. Lime and gypsum applications consistently resulted in seed and soil Ca levels above the untreated control.